The present invention relates generally to dental implants and, more particularly, to an immediate provisional implant that allows for fitting a fixed, provisional prosthesis after first stage surgery.
Dental implants are placed in the jaw to provide support for a dental restoration, fixed bridge or removable partial denture. Dental implants provide good chewing function and also improve the patient""s cosmetic appearance, thereby allowing the patient to smile, speak, and interact with others with greater confidence.
One type of dental implant widely used in the industry is a xe2x80x9cthreadedxe2x80x9d implant. Threaded implants have an externally threaded body segment, which is screwed into a pre-drilled hole (i.e., an osteotomy), in the patient""s upper or lower jawbone. Typically, the threaded implant body is formed with a central threaded socket accessible through the overlying gum tissue for receiving and supporting one or more dental attachments or components. Types of attachments and components that are received by the central socket include healing caps, impression copings and abutments. In turn, some of these attachments and components are useful to fabricate and/or to support a prosthodontic restoration, fixed bridge or partial denture. Exemplary implant constructions are disclosed in U.S. Pat. No. 4,645,453 to Nizick, U.S. Pat. No. 5,074,790 to Bauer and U.S. Pat. No. 5,312,255 to Bauer.
Dental implants are typically packaged as an assembly including all the tools necessary for the insertion of the implant into an osteotomy formed in the jaw. A typical threaded implant assembly includes a threaded implant body, an implant carrier, an insertion post, a coupling screw and a healing cap. The implant carrier, insertion post, and coupling screw are tools which are used for the insertion of the implant body. Typically, the implant carrier, insertion post and coupling screw are discarded after the implant body has been inserted into the osteotomy.
During the insertion procedure, the insertion post is securely coupled to the top of the implant body. The insertion post is held in place by a coupling screw, which traverses a central through-cavity in the insertion post and is threaded into the central threaded socket in the implant body. Typically, the bottom end of the insertion post has a hexagonal cavity that irrotationally mates with a hexagonal protrusion on the top of the implant, thereby preventing any relative rotation between the insertion post and implant body.
The coupling screw and insertion post are releasably coupled to an implant carrier. The implant carrier provides the dental practitioner with a means to grip and manipulate the assembly during the initial implantation procedure. Typically, the implant carrier includes a generally hexagonal internal passage at its bottom end which mates with a generally hexagonal outer surface of the insertion post. This allows torque applied to the carrier to be transferred, via the insertion post, to the threaded implant body. The dental practitioner uses the implant carrier to manipulate the implant body into the proper location within the jaw.
In use, the first step of the implantation procedure usually involves making an incision in the patient""s gum. A portion of the gum is then folded back and an osteotomy is drilled in the jawbone. The diameter of the osteotomy is equal to or slightly smaller than the diameter of the implant body. The implant carrier is then used to transport the threaded implant assembly to the surgical site. The implant carrier is used by the practitioner to manipulate the implant body into the correct position and then to partially screw the implant body into the osteotomy. Once the implant body has been initially placed in the osteotomy and tightened manually, the carrier is then pulled and/or loosened and removed from the dental implant assembly, leaving only the insertion post and coupling screw in engagement with the threaded implant body. A suitable wrench or dental hand piece is then used to engage the insertion post and drive the implant to its final depth within the osteotomy. The coupling screw is then unscrewed from the implant body, thereby allowing extraction of the insertion post and coupling screw from the patient""s mouth. Next, a healing cap is screwed into the exposed socket of the implant to cover the implant socket. The healing cap protects the implant socket against tissue in-growth during the initial healing period, and also prevents the entry of bacteria or other contaminants into the exposed central socket of the implant. Typically, the healing cap is housed in a cavity at the top of the implant carrier and is secured with a paper barrier until needed.
The insertion of the implant body and healing cap is followed by an initial healing period in which the bone is allowed to surround and retain the implant (i.e., xe2x80x9cosseointegratexe2x80x9d with the implant) and the gum tissue is allowed to heal over the implant body and healing cap. For implants placed in the mandible, healing typically requires about three months; for implants in the maxilla, the healing period typically requires about six months.
After sufficient osseointegration has occurred, the gum tissue is re-opened by making an incision and the gum tissue is once again folded back to remove the healing cap from the implant body. To remove the healing cap from the implant body, torque is applied to the healing cap to rotate the healing cap out of the implant socket. Typically, a removal tool with a hexagonal tip is inserted into a corresponding mating hexagonal recess located in the top center of the healing cap. Great care must be used to rotate the healing cap without also rotating the implant body. Any movement of the implant body relative to the osteotomy during the removal of the healing cap could damage the osseointegration between the implant body and the jawbone. Damage to the osseointegration is very undesirable and could endanger the entire dental restoration process by destabilizing the implant. In addition, any movement of the implant body could create unwanted gaps or spaces between the implant body and jawbone which could lead to infection by bacteria or other contaminants. After the healing cap has been unscrewed and removed from the implant body, a suitable healing abutment is attached. The healing abutment extends through the gum tissue overlying the implant site.
A second healing period then ensues in which the gum tissue is allowed to heal around the post-osseointegration healing abutment. Typically, this second healing period lasts from four to eight weeks. After this second healing period, the healing abutment is removed from the implant. Typically, an impression is taken of the patient""s mouth to fabricate a prosthesis or dental restoration. An abutment supporting the final restoration is attached to the implant. Lastly, the restoration is cemented or screwed to the abutment and/or implant to complete the placement of the prosthodontic restoration in the patient""s mouth.
The threaded dental implants described above, as well as other dental implants, such as xe2x80x9ccylindricalxe2x80x9d implants, require healing periods of three to six months or more. In the meantime, it has been desirable in the past to provide patients with temporary partial dentures or full dentures until the final restoration is in place. However, mastication forces on conventional temporary partial dentures and full dentures can harm or otherwise irritate the gum tissues overlying conventional submerged implants, bone grafts or tissue grafts and/or can also disturb the implants.
Accordingly, methods and structures are needed to provide protection to subcutaneous implants and the adjacent tissues from impinging mastication forces and moments during the healing period.
Briefly stated, the aforementioned needs are satisfied by a new method of providing permanent dental prosthesis that utilizes one or more immediate provisional implants to support a temporary prosthesis during the healing phase after conventional endosseous implant surgery. In particular, the immediate provisional implant(s) are positioned between conventional permanent implants, and are used to support temporary dental prostheses while the permanent implants are allowed to osseointegrate. Desirably, the immediate provisional implants are structured to satisfy the particular needs of this temporary support.
The immediate provisional implant (IPI) system of the present invention is advantageously designed to allow implant surgeons to place titanium alloy provisional implants in either the mandible or maxilla. Implant therapy often requires the patient to wear a provisional restoration for an extended period of time during the healing phase. An important advantage of the IPI System is to be able to deliver a more stable, temporary fixed prosthesis at the time of implant placement. This prosthesis removes the load from the soft tissues overlying subcutaneous implants surgically placed simultaneously or at about the same time (i.e., immediately prior or subsequent to implanting the immediate provisional implants) at adjacent sites during stage-one surgery.
By carrying the load of the temporary prostheses, the provisional implants allow improved healing of the permanent implant sites and at the same time provide the patient an aesthetic, functional, fixed provisional prosthesis after stage-one surgery. This is especially important for grafted sites. Placement of provisional implants enables the patient to wear an aesthetic, stable, fixed provisional prosthesis. This can improve treatment acceptance of grafting and implant procedures. Such use of provisional implant dental restorations also minimizes the risk of possible bone atrophy and bone shifting caused by reduced bone loading during the healing period.
The diameter of each provisional implant is preferably narrow enough to allow it to be placed between permanent implants at the time of surgery. The immediate provisional implant width or diameter is preferably between about 1 mm and 3.5 mm, more preferably less than about 3 mm, and in the illustrated embodiments the implants have a maximum outer thread diameter between about 2 mm and 2.8 mm (preferably tapered along its length). A non-linear taper is preferred in another embodiment, whereby the thread diameter rapidly increases near the top of the threaded segment adjacent the crestal bone. Advantageously, this allows that region of the threaded body which is mated with the denser cortical bone to resist applied moments, with less damage to the less dense bone beneath. The non-linear tapered implant may be generally characterized as having a flared upper segment having a relatively large taper angle, a generally cylindrical intermediate segment and a lower tapered segment having a relatively small taper angle.
The overall length of the preferred immediate provisional implant is preferably greater than about 17 mm, more preferably greater than about 20 mm, and most preferably about 22 mm. This length includes an anchor segment designed to be anchored in cortical bone to a depth greater than that of adjacent permanent implants. This anchor segment is threaded in the illustrated embodiments, and is preferably 12-16 mm (14 mm preferred), sufficient to support the forces on a provisional prosthesis. A flared taper at the proximal end of the implant facilitates enhanced engagement of the cortical bone layer, giving the immediate provisional implant according to the invention better initial stability without osseointegration. This allows the underlying conventional implant or graft to heal without premature loading.
One preferred embodiment of a provisional implant according to the invention also preferably includes an integral extension from the anchoring segment, preferably greater than about 3 mm, more preferably greater than about 5 mm, and most preferably about 7.34 mm. The extension includes a portion extending above the crestal bone and serving to receive a temporary dental prosthesis or restoration.
The immediate provisional implant is preferably of single piece construction and is preferably fabricated from titanium alloy for strength. The extension from the anchoring segment preferably includes an abutment portion and an intermediate bendable neck to allow for abutment parallelism. The hourglass shape of such a neck not only provides the desired flexibility, but can also help prevent migration of soft tissue over the implant abutment.
The integral implant and abutment design provides predictable retention and support of the temporary prosthesis. Machined titanium copings, which become integrated into the final prosthesis, engage the tapered design of the abutment resulting in retention, stability and a precise margin fit of the temporary restoration. The provisional restoration may be fabricated by the restorative dentist or clinician directly over the titanium coping. Optional analogs are also preferably available if it is preferred or indicated to fabricate the restoration using a laboratory model and a cast stone replica of the patient""s mouth/jaw.
Advantageously, the IPI System can be used for fully and partially edentulous patients. Two to three immediate provisional implants can be used for a partially edentulous patient. On average, a fully edentulous case employs four-to-six immediate provisional implants (preferably, five in the maxilla). The immediate provisional implants are preferably placed at a minimum distance of about 3.0 mm from conventional submerged root form implants. The IPI System thus eliminates the need for temporary partial dentures that can otherwise harm or irritate conventional submerged implants or bone grafts. Once the permanent implants are fully healed and osseointegrated to the patient""s jaw bone, the immediate provisional implants can be partially or fully removed with minimal discomfort to the patient. Patient acceptance for conventional implant procedures may increase due to the fact that the immediate provisional implant system allows them to leave the office after stage-one implant surgery with a fixed provisional or temporary restoration.
In accordance with one aspect of the invention, a method of providing permanent dental prosthesis to a patient who is at least partially edentulous includes providing a permanent implant within bone in a patient""s mouth at a permanent implant site, and providing a provisional implant within the bone in the patient""s mouth adjacent the permanent implant site.
In accordance with another aspect, a method provides a fixed, temporary dental prosthesis during a healing period for permanent implant osseointegration. The method includes implanting permanent implants in a bone within a patient""s mouth. Provisional implants are also implanted in the bone at positions alternatingly adjacent the permanent implants. Each of the provisional implants includes an abutment protruding out of the bone. The temporary dental prosthesis is adhered to the abutments. After a healing period, during which the permanent implants osseointegrates, the temporary dental prosthesis is removed from the abutments.
In accordance with another aspect of the invention, a system provides an interim dental prosthesis while allowing osseointegration of a permanent implant. The system includes at least one permanent implant for anchoring within a patient""s mouth. The system also includes a plurality of provisional implants for anchoring adjacent the permanent implant. A temporary dental prosthesis is configured to be supported upon the provisional implants.
In accordance with another aspect of the invention, a system provides an immediate provisional dental implant. The system includes a plurality of provisional dental implants. The implants each include a threaded body segment, a neck segment integrally formed with and extending from the body segment, and an abutment integrally formed with and extending from the neck segment. The body segment preferably has a maximum width no more than about 3.5 mm. The neck segment includes a torque accepting feature. The system also includes an osteotomy drill with a diameter less than the maximum width of the threaded body. A torque-supplying driver tool is adapted to engage with the torque-accepting feature of each provisional dental implant in order to impart rotation for self-screwing the provisional implant into an osteotomy drilled by the osteotomy drill.
In accordance with another aspect of the invention, an integrally-formed immediate provisional dental implant extends along an implant axis. The implant includes an abutment adapted to bond with a dental prosthesis, a flexible neck segment connected to the abutment, and a threaded body segment. The body segment has threads extending helically about the implant axis. The thread diameter tapers non-linearly from a maximum adjacent the neck segment to a minimum at a distal end. For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above.
Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.